Brain monoamine oxidase will be purified. The content of free and covalently bonded FAD in the enzyme will be determined. Bovine aorta amine oxidase will be investigated. The enzyme is able to inactivate the neurohormone norepinephrine at a slow rate. The complete physicochemical properties of the enzyme will be determined. The kinetics of the oxidation of substrate by bovine liver monoamine oxidase will be investigated by stopped ffow and temperature jump methods. By these techniques, it is hoped that the formal mechanism proposed for the enzyme and which was obtained by steady-state methods can be confirmed and extended.